Our son spent a week in hospital when he was 3 weeks old due to 2 collapsed lungs. His lungs were then very weak. Our house is 90 years old and over winter was always damp. Our son had to go to hospital each winter due to the damp, cold air. So, we got an HRV installed. Now our son has not had to go to hospital in the last 3 years! Not only that, our home is easier to heat and the air is dry.